Sulfur vaporization



superheat sulfur vapors.

Reissued Jan. 2, 1951 SULFUR VAPORIZATION Charles A. Porter, Crystal Lake, and Milton M. Marisic, Elgin, IlL, assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio Original No. 2,508,292, dated May 16, 1950, Serial No. 589,679, April 21, 1945. Application for reissue August 10, 1950, Serial No. 178,732

(Cl. 23-224) Matter enclosed in heavy brackets appears in the original patent but forms no part of this 13 Claims.

reissue specification;

This invention relates to method and apparatus for vaporizing and superheating sulfur.

Vaporization of sulfur and superheating of sulfur vapors are two of the most difficult problems encountered in chemical operations. Sulfur ordinarily contains a small amount of both organic and inorganic impurities which deposit on the vaporizing surfaces when sulfur is vaporized causing formation of coke and scale deposits which necessitate frequent cleaning of the still in order to obtain satisfactory heat transfer rates without exceeding safe metal temperatures. In superheating sulfur vapors the principal difiiculty is encountered in the corrosive effect of sulfur on all common metals and alloys at elevated temperature. Not only is the life of the heating element shortened, but scale formation on the surface of the heating elements greatly reduces the heating transfer rates. Many chemical syntheses involving use of sulfur would be possible if a. satisfactory method and apparatus for vaporizing and superheating sulfur was available.

An object of this invention is to provide an apparatus for vaporizing sulfur.

A further object of the invention i to provide a method and apparatus for superheating sulfur vapors without any substantial corrosion of the apparatus.

Further objects of this invention will manifest themselves from the following description and the accompanying drawings, of which Figure 1 is a diagrammatic elevational view of one form of apparatus for carrying out the invention; and

Figure 2 a diagrammatic elevational view of another form of apparatus for carrying out the invention.

' Referring to Figure the numeral I designates a pump by means of which molten sulfur at a temperature between approximately 250 and 300'F. is pumped through line 2 into vaporizing and superheating column or chamber 3. Column 3 is lined with refractory material such as carborundum, alundum, quartz, fire brick, or the like,

which is not attacked by sulfur to any substantial extent. Column 3 is filled with a bed of pelleted, fragmentary or granular refractory material such as carborundum, alundum, quartz or fire brick, heated to a temperature somewhat above the temperature to which it is desired to Upon contact of the molten sulfur with the moving bed of refractory material the sulfur is vaporized and passes upward through the bed in direct heat exchange with the hot refractory material and becomes heated to the desired temperature. The super matter printed in italics indicates the additions made by reissue heated sulfur vapors leave the top of chamber 3 through line 4 and are charged to a system in which it is desired to use the superheated sulfur vapors, such as for example a reactor for making carbon disulfide by reaction of superheated sulfur vapors with methane, or other hydrocarbon gases, in the presence of a suitable catalyst such as silica gel, activated alumina, activated clay or synthetic silica-alumina catalyst. The molten sulfur enters the chamber 3 preferably some distance from the bottom thereof, but below the middle of the column.

superheated steam is admitted to the bottom of the column 3 through valve-controlled pipe 5 at a temperature of approximately 900950 F. in order to purge residual sulfur from the refractory material. An outlet 6 is provided between the line 5 and line 2 for drawing off the steam and sulfur vapors contained therein from the purged refractory material. The line 6 is connected to a condenser l maintained under atmospheric or superatmospheric pressure. Water, steam and sulfur in molten form pass from the condenser l to the receiver 8. Sufficient pressure may be maintained in the condenser and receiver 8 so that substantially all the steam and sulfur is condensed to liquid or molten state. Pressure in the column 3 will be somewhat above that maintained in the condenser 1 so that the purging steam and sulfur vapors contained therein will pass through line 6 instead of passing upward through the column 3 to the outlet 4. It will be understood, of course, that a certain portion of the purging steam will pass upward through column 3 and be eliminated through line 4. From the receiver 8 molten sulfur is recycled through line 9 by means of pump I0 through line H controlled by valve I2 to line 2. Hot water and steam are withdrawn from the upper portion of receiver 8 through valve -controlled line l3.

Hot refractory material is intermittently introduced into the vaporizer and superheater 3 from hopper l4 through line l5 controlled by valve IS. The refractory material is intermittently withdrawn from the bottom of column 3 through line ll controlled by valve I7 and passes to hopper l8. At such time as hopper I4 is being emptied into column 3, valve IS in the outlet of hopper f8 and valve 2!! in the inlet to hopper M are closed. Refractory material is preferably withdrawn from column 3 into hopper II! at the same time as hopper I4 is emptied in column 3. When hopper I4 is empty and hopper l 8 is full of refractory material valve It in the outlet of hopper l4 and valve ll in the inlet to hopper l8 are closed and the flow of refractory material in the chamber 3 is interrupted. Any steam which accumulates in the hopper I8 is removed from the top thereof through valve-controlled line H after which refractory'material from hopper I8 is discharged therefrom through valve 53 and the refractory material passes into receiver 22.

During the time that steam iswithdrawn from the hopper I8 hopper I4 is depressured and sulfur is withdrawn therefrom through valve-controlled line 23. The sulfur vapors may be condensed and recycled to line 2 through a line not shown. Valve 20 is then opened and hopper I4 is then recharged with hot refractory material from receiver 24 through valve 20. As soon as hopper i4 is filled with hot refractory material valve 20 is closed and any flue gas which may have accumulated in hopper I4 is exhausted therefrom through valv econtrolled line 23. Hopper I4 is then pressured with sulfur vapors from line 4 by opening valve 25 in line 26 and permitting sulfur vapors to flow into the hopper I4. When the pressure between V chamber 3 and hopper l4 has been equalized valve I6 is again opened and the refractory material is permitted to flow fromthe hopper l4 into top of chamber 3 and valve i1 is opened to permit refractory material to be withdrawn from the bottom of chamber 3. I

From the receiver 22 granular refractory material passes continuously through line 21 to elevator 28, which may be of the bucket, or any other suitable type, and is conveyed to kiln 29 through line 30. The refractory material passes downwardly through kiln 29 and is heated during its downward passage to the desired temperature by burning in the kiln combustible gases mixed with air charged thereto through manifold 3l and valve-control ed lines 32, 33, 34, 35, and 36 at j spaced points along the kiln. Any suitable liquid,

powdered or gaseous fuel may be burned in the kiln 23 such as natural or producer gas, furnace oil, acid sludge, or tar. A portion of the heat may be supplied by combustion of organic matter deposited on the refractory material during the sulfur vaporization step. Some crude sulfurs contain substantial amounts of organic matter which is removed during the vaporization and superheating step and left deposited in the form of coke on the refractory material. This organic matter is burned from the refractory material in kiln 29 by supplying sufficient excess of air to burn the organic matter.

Flue gases leave the kiln 23 through valvecontrolled lines 31, 38, 39, 40 and 4|. The heated refractory material leaves the bottom of the kiln through line 42 controlled by valve 43 and is carried by elevator 44 to line 45 which empties into the top of receiver 24. Any residual flue gas in the heated refractory material is withdrawn from receiver 24 through valve-controlled line 43.

In the apparatus just described, in addition to the vaporizing and superheating chamber 3, hoppers l4 and 18 are preferably lined with refractory material, as well as such other portions of the apparatus which come in direct contact with sulfur vapors at high temperature.

Instead of purging the refractory material by injecting superheated steam through line into the bottom of chamber 3 and withdrawing the steam and contained sulfur vapor through line 6, the refractory material may be purged in hopper l8 by injecting superheated steam into the bottom thereof through valve-controlled line 41 and from the top of hopper l8 through valve-con- 4 trolled line 48 which, in turn connects to line 6.

It will be apparent that the apparatus shown in Figure '1 may be used to purify contaminated sulfur. In such case the refractory material will be heated to a temperature sufficient only to vaporize the sulfur. Such temperature may be approximately 1000 to 1100 F.

Referring now to Figure 2, solid sulfur in small pieces or in powdered state is fed from hopper 50 through valve Si by means of screw conveyor to a sulfur melter 53. The sulfur is melted in melter 53 by direct contact with superheated" steam or hot water under pressure. Sulfur is charged to the 'fnelter 53 intermittently. When the melter is filled with sulfur, valve 5| is closed and superheated steam is introduced into the bottom of melter 53 through valve controlled line 54. Melted sulfur and water are transferred from the bottom of melter 53 through line controlled by valve 56 to a sulfur-water separator 51. Valve 56 is then closed and melter 53 depressured by opening valve on line 51 on the top of the melter to permit steam to escape and is then recharged by opening valve 5| and operating screw conveyer '52. Since melter 53 is operated intermittently it should be made sufficiently large to provide a sufficient supply of molten sulfur for separator 51 so as to enable sulfur vaporizing and superheating operation to be carried on continuously.

Water is removed from the top of separator 51 through valvecontrollel line 58. Molten sulfur at a temperature of approximately 25D275'F. is

withdrawn from the bottom of separator 51 through line 59 by means of pump 3'0 and pumped through line 6| into vaporizer and superheat'er chamber 62 at a point below the middle thereof, but some distance from the bottom thereof.

Molten sulfur is discharged into chamber 52 and are returned to sulfur melter 53. The sulfur condenses inmelter 53 and the steam wholly or partially condenses to water at the same'tlme as the solid sulfur is heated to the melting'point. Only sufficient superheated steami's'admitted to the melter .53 through line 54 to supply heat in addition to that supplied through line 58 necessary for melting sulfur in'melter 53.

.Refracto'ry material leaves the bottom of chamber 52 through either lines 61 or 63 controlled by valves 69 and"), respectively. If valve '10 is closed and valve "69 is open'the refractory material will pass into hopper '1]. While refractory material is passing into hopper'll. valve 12 in the outlet 13 connected to the bottom of hopper H is closed. While refractory material is flowing from chamber 62 intohopper 'H refractory material is flowing from hopper T14 through line [5 controlled by valve 13 to the bottom of elevator 11. Elevator H is of the bucket, or any other suitable type.

After hopper 14 is emptied, valve 16 isclosed and valve H! is opened to permit the refractory ma ia to assfmm he. bg mmei cheape 5 through line 68 into hopper 14. As soon as hopper l4 is full' of refractory material, valve I is closed and any steam accumulated in hopper 14 is. withdrawn through valve-controlled pipe 11-. r 7

After hopper I I is filled with refractory .material, valve 69 is closed and the hopper is depressured by drawing off steam through valve-conftr'olled line 18. Valve .12 is then opened and the refractory material passes from hopper II through line 13 to the elevator "I1. In this way refractory material is continuously withdrawn from chamber 62 through either, hopper II or hopper I4 and supplied continuously to the elevator I1.

: Instead of purging sulfur from the refractory material by admitting superheated steam into the bottom of chamber 62, sulfur may be purged from the refractory material in hoppers 'II and 14 byadmitting superheated steam into the bot- .tom thereof through valve-controlled lines "I9 and 80, respectively, and withdrawing the steam and sulfur vapors from the top of hoppers II and .14 through valve-controlled lines 8| and 82, respectively. From thelineBI the steam and sul- ;fur vapors pass to line 95 and then to sulfur ;melte r 53. 2 1 Refractoryv material is charged from the top of the elevator 17 through line 83 to kiln 84.- Kiln .84 is heated by means of a mixture of air and combustible gas, liquid or powdered fuel introduced at spacedpoints through valve-controlled .lines 85 and '85. Combustion gases are with- .drawn from the kiln through valve-controlled .lines 81, 88 and 99. If desired, combustion gases from the kiln may be circulated'through the elevator 11 and withdrawn from the top. thereof through valve-controlled line 90 in order to preheat the refractory material before it is introduced. into the top of the kiln. If for example, the refractory material is heated to approximately1400 F. in the kiln, ,it maybe preheated to approximately 1200 F. in theelevator by circulating the flue gases therethrough. Heater refractory material leaves the bottom of the kiln 84 through either lines 9| or 92 controlled by valves 93 and 94, respectively. When refractory material is discharged from the kiln through line 9| into hopper 95, valve 95 in the outlet 91 of hopper 95 will be closed. Valve 94 inthe inlet 92 to hopper 98 will be cl0sed,.and valves 99 in the outlet I00 of hopper 98 will open so that refractory material can flow from hopper98 continuously into the top of the vaporizer and superheater 02., As soon as hopper 98 is empty, valve .99 and valve MI in line I92 are closed and sulfur ;vapors are exhausted from .the hopper through {valve-controlled line I03. I Sulfur vapors exhausted through line I03 maybe recycled before or after condensation to separator 51 by means of a line not shown. After hopper 93 is depressured valve 94 is opened to permit hot refractory material to flow from kiln 84 into the hopper.

Hopper 95 is filled with hot refractory material during the period that refractory material is fed from hopper 98 into the chamber 62. After hopper 95 is filled, valve 93 is closed and hopper 95 is pressured with sulfur vapors through line I94, controlled by valve I05, connected to line 63. Hopper 95 is now ready to feed hot refractory material to chamber 62 by opening valve 96. Hopper 95 is exhausted of sulfur vapor through valve-controlled line I05 when it is empty and the sulfur vapors may be recycled to separator 51. Hopper 98 is pressured by admitting sulfur fragments is heated to 1400" vapors thereto through line I02 controlled by valve IllI. after it is filled and valve 94 has been closed.

Flue gas may be removed from the refractory material in hoppers 95 and 98 through valvecontrolled lines I06 and I03, respectively, prior to repressuring with sulfur vapors. v

It will be understood in connection with Figure 1 that the purging steam with contained sulfur vapors may be used to melt solid sulfur, as described in connection with Figure 2, and that sulfur melting in Figure 2 by means of the purging steam may be omitted and sulfur melted by extraneous heating means only.

The method and apparatus described and shown-in connection with Figure 2 have the advantage over those described and shown in Fig ure 1, in that in Figure 1 the temperature to which the refractory material can be heated is limited by the ability of the metal of which the elevator is constructed to withstand high temperatures. At the present time, materials available for such construction are capable of standing a maximum temperature of about 1200 F. with the result that the limit to which the refractory material can be heated is about 1200 F. and the temperature to which sulfur can be heated by means of the refractory material is somewhat below 1200 F.

Theapparatus of Figure 2 is not limited as to temperature because the heating kiln follows the elevator. Therefore, much higher sulfur vapor temperatures can be attained in conjunction with the construction shown in Figure 2. I

In both Figures 1 and 2 all parts which come in contact with hot sulfur vapors are preferably made of or lined with refractory material which is not substantially attacked by sulfur. In both Figures 1 and 2 the flow rate of refractory material through the vaporizing and super-heating chamber, and the quantity of sulfur charged is so regulated that the temperature of the refractory material leaving the bottom of the chamber is above the vaporizing temperature of sulfur at existing pressure.

, Asan example of an operation carried out in the apparatus shown in Figure 2, alundum, as the refractor, in the form of 6 to 10 mesh size F. in the kiln 84 by the combustion of natural gas. The granular alundum moves continuously through the kiln and passes to either hopper 95 or 98 and therefrom as previously explained through chamber 62.

Molten sulfur at a temperature, of 270. F. is

pumped continuously through line 6i to chamber 02 whereinon contacting the moving granular alundum it is vaporized and superheated to 1200 F. before leaving chamber 62 through lines 63 and 04. Molten sulfur is charged to 52 at the rate of 24.7 pounds of sulfur per hour and granular alundum passes through chamber 62 at the rate of 1 cubic foot per hour. Steam at 900 F. is introduced into chamber 62 through line 65. This steam amounts to about 3% by weight of the sulfur charged to chamber 62. The temperature of the alundum particles leaving through the bottom of 62 is 900 F.

The word granular employed in the following claims is intended to connote not only irregularly shaped, particulated or discrete refractory materials, such as fragmented or granular solids,

. w? tisclaime :w

LI'The methouof iizim snlfn'xr comprising circulating solid [comminuted] granular material resistant. to.- sulfur attack through: a heater and vaporizer, heating, said material. to a. tempera,- tmte' above. the boiling point of sulfur in heater by direct contact, with hot,v combustion gases removing combustion gases from the said. material passes through the: heater and vaporizer in. the form of a moving, bed.

3.. Method in accordance with-claiml in which n said. material passes continuously through heater and vaporizing zone in. the. form. of amouing. bed. I

4., Method in accordance with claim 1 inwhich the [comminuted] granular material. is mechane ically conveyed, from theheater to the. vaporizing zone.

5. Method in accordance. with cl'aimlinwhich the, [comminut'ed'j' granular material is mechanical'ly conveyed from the vaporizing zone, to the heater and" is caused to flow by gravity from the heater to the vaporizing zone.

6: The method of vaporizing sulfur comprising heating [comminutedl granular refractory material to a temperature above the boiling. point of sulfur by directcontactwithhotcombustion gas, separating" combustion gas from the hotrefractor-y material; charging said hot refractory material to a vaporizing zone linedwith refractory material; charging molten sulfurto said vaporizing zone in direct contact with said hot refractory material; contacting said sulfur and refractory material for a period of-timesuificient to vaporize the sulfur a superheat thevapors, withdrawing superheated sulfur vapors from the-vaporizing' zone withdrawing said [commihuted] gram ular refractory material from said vaporizing zone atsuch rate as to remove it fromsaid zone before its temperature dropsbelowthe boiling point-of sulfur, recycling the withdrawn refractory material to the heater and purging sulfur from said. refractory material prior tome-cycling" it to. the. heater. 1

2.1 Method in accordance with claim 6 in which superheated. steam. is. used to purge sulfup from the. ref ractory material. and; the resulting steam! sulfurvapor mixture is. user to melt to charged to. the; vaporizer.

Method in accordance with. claim 6 in; which the [comminuted] granular refractory material is heated: to approximately 1200, F; before: charging-it to. the, vaporizing zone.

9.. Method in accordance with claim 6 in which the [somminuztedl granu'larrefractom is'heatedato approximatelyrl l flfl F. priorto chars.- it; to the vaporizing. zone.

re. The; method of. vaporizing sulfur comprismg. alternately heating. [commuted] granular solid: materialv not; reactive: sulfur at temxperatures of boiling sulfur to a temperatme: sub"- stantialhr above. the boiling point of sulfur and contacting said heated: material. with sulfur in be vaporized, discontinuing contact of sulfur-:with said solid: material before the temperature thereof is reduced below the boiling temperature. of sulfur, purging residual sulfur fromthe solid mate.- riaf and repeating the heating of the: solid materialfandt-the vaporization of sulfur therewith.

'1 L; The method of vaporizing sulfur compris mg, circulating E'commi'nuted]gmnularsolidmaterialinot reactable with sulfur at temperatures of boiling sulfur through a heating and vaporizing Zone; heating said material insaid heating zone to a temperature substantiallyahove the boiling point of sulfur, passing said heated material to said?- vaporizingzone. and there contacting with sulfurto be vaporized, withdrawingsulfur vapors fromsaid vaporizing zone-withdrawingsaid mat'eri'al from said vaporizing zone before the tom-'- perature-thereofis' reduced below the boiling temperature of sulfur, purging residual sulfur therefrom and} recycling said material t'o-sai'd heating zone.

12. The method in accordance with claim 1); in which the solid material is a refractory" material".

1-3; The method in accordance with claim 11 in which the sulfur iscontactecl with a hot material in: a moving bed" of the material.

CHARLES A. PORTER. MILTON MARISIC. REFEREBQES men The following references. are. of record} in. the file. of. this. patent or the. original patent;

STATES] PATENTS Tuhle' May-9 1944 

